Polar bears are the latest flashpoint in the intensifying fight over whether the United States should drill for oil in Alaska's Arctic National Wildlife Refuge (ANWR).

President George W. Bush has reaffirmed the case for the drilling — in the name of energy security — since the events of 11 September. But environmentalists, facing an uphill struggle to block it, are threatening to sue the administration for allegedly covering up information on the impact of such drilling on the polar bear population.

Research does not seem to back the environmentalists' claims, however. Recent studies — albeit part-funded by the oil industry — suggest that mother polar bears will not abandon their young as a result of oil exploration and extraction.

Steven Amstrup, a biologist with the US Geological Survey in Anchorage, has surveyed polar bears in Alaska for over a decade. He estimates that about 25 dens are set up by the bears each year in the region of the ANWR where drilling is set to take place.

Environmentalists argue that drilling might disturb some female polar bears so much that they abandon their dens and cubs. But Amstrup, whose assessment is partly based on data showing that dens are widely dispersed, says that activity in a given area would disrupt few, if any, bears.

In earlier work, Amstrup found that the bears are generally tolerant of outside disturbance (see Arctic 46, 246–250; 1993). High-impact activities could also be prevented during the denning season. “There are a lot of options for management,” he says.

The Center for Biological Diversity, an environmental pressure group based in Tucson, Arizona, has nonetheless petitioned the US Department of the Interior to release a 1995 assessment of whether the United States complies with a 1973 international agreement to protect polar bears. Congress requested the report but has yet to receive it, as the interior department says it wants to retain it until a new polar bear treaty, agreed with Russia last year, is reviewed by the Bush administration.

Kieran Suckling, the centre's executive director, calls this a “stall tactic” and says the group may use legal means to force the document's release. He believes the report suggests that development in the ANWR could break the 1973 agreement.